The Cooperation of Dissimilar Mating Types
by JunoInferno
Summary: A certain Ginger Time Baby has questions about where babies come from. The Doctor and Donna have different ideas- as usual- about how to answer those questions. Rated M for paranoia about grown-up topics but really, nothing scandalous.


Author's Notes: I do not own the Doctor or Donna. Why not? Anyway, this is part of the Regarding Mrs Smith ficverse, though I do not think you need to read all that to follow. Summary: the Doctor and Donna have an adorable ginger Time Baby called Zara. See? I've rated this M because I don't understand where this falls on the ratings at all and I am paranoid. Please let me know what you think and happy reading!

* * *

"Daddy, where do babies come from?"

The Doctor dropped his spanner on his foot as he turned to Zara. "Ow!"

"Are you okay?"

"Fine, fine," said the Doctor, collecting the spanner. He was situated in one of the floor panels of the console room. Zara was perched at the top. His notion was that she would be paying attention to what he was doing as her first steps towards operating the TARDIS. Her mind wandered, though. The Doctor thought that must have been her human side, endlessly wandering along a chain of thought he couldn't fathom. Donna, of course, accused him of contributing that particular characteristic.

"So?"

He looked back at her. "So?"

"Where do babies come from?"

"Well, Zara, as you well know you lived in your mummy. So, you came from her. Not the case with all species in the universe. There are some species where the father carries the young and some with an egg or possibly air bubbles in water in more aquatic environments or take the Adipose-"

"How did I get there?"

The Doctor froze. "Sorry?"

"How did I get inside Mummy?"

"Well, uh, really, Zara, I-"

"Don't you know?"

"Yes, I know!," the Doctor said insistently. He searched for an answer. "If you must know, your mother and I each supplied a gamete, they combined into a zygote, which divided into multiple cells carrying your genetic code, they continued the process of division and multiplication forming your organs, tissues and so on all stabilized by your dependence on Mummy. There, does that satisfy you?"

"Yes," said Zara.

* * *

It was the end of another busy day for Donna. She had put the baby to bed and then Chloe. Ready to put her eldest down for the night. Donna walked into Zara's room. She was pleased to see her already in bed with the dog, Esther, settled at her feet.

"Oh, look at you!," said Donna as she sat on the bed next to Zara. "Already dressed in your pajamas. How very grown-up you are."

Donna started the nightly ritual of arranging Pooh Bear and Mister Scallofrax on either side of Zara.

"Mummy," said Zara. "Can I ask you something?"

"Of course, sweetheart, what is it?"

"How did gametes get inside you?"

Donna frowned. "Gametes?"

"Daddy said I came from gametes inside you."

Donna nodded. "Alright, that's technically correct."

"So, how did they get inside you?"

"Zara, just out of curiosity, what question did you ask Daddy to end up with that answer?"

"I asked where babies came from."

Donna nodded. "Ah."

"Isn't that where?"

"Yes, but, Daddy is missing some of the big points," said Donna. "What made you ask? Was it your little friend, Alexandra and her new baby brother?"

Zara nodded. "Her mummy said a stork brought him."

"A stork?," Donna asked incredulously. "Are people still saying that? What is this? The eighteenth century?"

"I didn't believe it," said Zara.

"I'm going to go have a chat with Daddy. Would you do Mummy a favor and wait until morning so we can give you a proper answer?"

Zara nodded.

"That's my girl," said Donna, giving her a kiss on the forehead. "Sweet dreams."

* * *

Donna walked into the console room and cleared her throat.

"Oh, Donna," said the Doctor, turning from his latest project on the control panel, "children asleep?"

"Yes," said Donna. "I was just wondering if you could enlighten me on something."

"Of course I can," the Doctor said with a smug grin.

"Yes, I was just wondering exactly how the gametes that grew into Zara got inside me?"

The Doctor's face dropped. The smug grin was gone. "Ah, yes, that."

"That," Donna repeated.

"She just had some elementary questions."

"You know what question she was asking, Doctor. She wanted to know where babies come from."

"I blame that nursery school!," said the Doctor decisively. He was even pointing an accusatory finger.

"What?," asked Donna, not following.

"All those unsavory characters. That Easter performance was downright subversive."

Donna shook her head. "The most unsavory character there is a little boy who eats paste."

"Yes, but what about that one who pinched her?"

"I think he just fancied her."

The finger came out again. "There! You see!"

"No, I don't see," said Donna.

"A pinch, then he fancies her and now we're getting questions about reproduction!"

"She's four now, it's perfectly normal-"

"Not for Time Lord children!"

"Ah," said Donna.

"Ah?"

"Yes, 'ah' as in 'Ah, we're having one of those Human Time Lord disparities'," said Donna. "So, tell me, when did little Time Lords learn about the birds and the bees?"

"Not until a decent age."

"What? Your all powerful, all knowing species just skipped over sex?"

"There was a unit in the thirty-sixth form."

Donna tried to do the mental math. "You were eight when you went to school, so you were- you were forty-four?! That's older than me. You went that long before anyone told you about sex? Didn't you wonder?"

"All babies on Gallifrey were not born. Most, in fact, were loomed. The ones who were born didn't go around bragging about it and certainly didn't ask questions about it!"

"What do you mean they were loomed? They weren't just knitted out of some mad Time Lord yarn, were they?"

"No, Donna, it was a machine that used cells from two donors to recombine them and create offspring."

"You weren't loomed, though?"

"No."

"And your children?"

"No."

"So, what did you tell them?"

"First of all," the Doctor stammered, "I didn't tell them anything until their betrothals."

"What? To get them ready for the wedding night?"

"No," the Doctor sighed, running his hand through his hair. "There is a betrothal period prior to what you consider a formal engagement. The betrothed have an understanding, but either party can back out whenever they like. It is during this period that the betrothed will..."

"Will?," Donna prodded.

"Will try the marital bed."

"What? Test the mattress?," teased Donna.

"Donna..." the Doctor whined.

"God, you sound like something out of a Victorian drama!," said Donna. "Have sex? Sleep together? Can't believe you didn't go for copulate."

"Donna..."

"I always thought you were spouting Gallifreyan dirty talk in my ear," said Donna. "Now I don't think it is. Is it poetry or equations?"

"Really, Donna?"

"How old were you when you were betrothed?"

"I don't see why we have to get personal."

"Well, I'm your wife for one thing."

"Oh, right," said the Doctor.

"Oh, come on," said Donna. "I was seventeen when I had sex."

The Doctor's face froze. Donna thought she might have been watching him turn even paler than he was. Those freckles were definitely losing some of their color.

"Doctor?"

"Seventeen?! You were seventeen!"

"Come on. You knew you weren't the first."

"It's not that! It's- seventeen?!"

"Stop looking at me like I'm the whore of Babylon!," said Donna.

"No, she was much worse," said the Doctor. He realized what he had said as soon as Donna's jaw dropped. "That is not what I meant!"

"I should hope not, sunshine."

"Seventeen is practically a toddler on Gallifrey, that's all," said the Doctor.

"So?," asked Donna.

"So?"

"So, how old were you when you 'tested the marital bed'?," asked Donna.

"Two hundred."

"Two hundred? Well, that explains why your lot walked around angry so much. Explains some things about you."

"So, you see that there is no need to discuss such matters with Zara at such an impressionable age."

"No, I don't see that."

"Donna..."

"No, no matter how many times you whine out my name, I'm not going to change my mind. Maybe your people didn't think much of sex, but I don't know if you've noticed it, the human race is obsessed with it. My mum told me practically nothing except when I was fifteen and she said if I got pregnant out of wedlock, it would give my dad a heart attack. What good did that do me? My first time was with Jimmy Fielding in his parents' caravan while it was still in the front drive and it was rubbish-"

"Was it?," the Doctor asked, his voice tinged with the slightest bit of glee.

"Yes," said Donna, crossing her arms. "Anyway, that led to my whole string of lousy boyfriends because I was looking for something and I didn't even understand what it was and it was all topped off with Lance! So, sorry, I'm not going to try to lie to her or confuse her. She doesn't need the details, but the way you made it sound babies come out of a test tube and that's all they are when you know better."

The Doctor nodded. "What do I do?"

* * *

The Doctor awoke to see Zara standing next to his and Donna's bed.

"Mummy said I'd get a proper answer now."

Donna stirred and looked over.

The Doctor turned to Zara. "Are you sure you wouldn't like a pony instead?"

"Doctor..." Donna warned as she sat up. She held her arms out for Zara. "Come on."

Zara climbed up between her parents. She looked up expectantly. "How did the gametes get in?"

"Well..." said the Doctor drawing out that one syllable word for everything it was worth.

Donna spoke up. "Mummies have one type of gamete called an egg. It's already inside us. Daddies have another kind called a sperm that they put inside the mummy."

"Of course, the volume of an ovum is approximately one hundred thousand times that of the sperm," said the Doctor.

Donna shot him a look.

"It's called anisogamy!," the Doctor said emphatically.

"Does it matter?," asked Donna.

"In my opinion, yes."

Donna rolled her eyes.

"Fertilization risk? Cooperation of dissimilar mating types? These things are important, Donna."

"How?"

"Well, you see, Zara," said the Doctor, "throughout evolution smaller cells would have evolved-"

Donna interrupted. "Zara, did you mean how does the daddy put the sperm in the mummy?"

"Yes," she said with a frown.

"When mummies and daddies love each other very much and decide they want to make a baby, the daddy puts his penis inside the woman's vagina." She looked up at the Doctor. "Did your respiratory bypass just kick in?"

The Doctor could only nod with wide eyes. Zara looked back at Donna in concern.

"He's fine," said Donna. "It's a Time Lord thing. Have I answered everything?"

"Why?"

"Why what?," asked Donna. Just then she noticed the Doctor's lungs had returned to functioning.

"Why do mummies and daddies want to make a baby?"

"Seriously?," asked the Doctor.

Zara nodded.

"Do you know what it's like when you really love something? Take bananas. You love bananas."

"Yes," said Zara.

"So, you want banana everything. Banana biscuits, banana bread, banana cake-"

"Banana ice cream!," Zara interjected.

"Exactly!," said the Doctor. "That's what it's like when you love someone-"

"The right someone," Donna added.

"It's what it was like when I fell in love with Mummy. I couldn't get enough of her, but there's only so much Mummy to go around so we had to have something that we would love just as much as we loved each other and that was you."

"Okay," said Zara, climbing down.

"Do you have any other questions, sweetheart?," asked Donna.

"No," said Zara, walking back to her room.

"Did you want breakfast?"

"No."

"It's about three in the morning," the Doctor explained as Zara's door shut.

"What?"

"You did say she could have a proper explanation in the morning," said the Doctor.

"I should have specified," said Donna.

"Yeah," agreed the Doctor.

"You know, for someone who hasn't given a sex talk to anyone below the age of two hundred, you did rather well, spaceman," said Donna.

The Doctor smiled, pleased at her reaction. "I am a bit disappointed we didn't get to use the diagrams, though."

"Yes, you did go to a lot of effort," Donna agreed. "Maybe Chloe or Geoffrey will want to see them."

The Doctor groaned. "You mean we have to do it again?"

"What? Do you want Geoffrey to pick up everything from Jack?"

The Doctor's eyes widened again. "No, no, definitely no."

"Cooperation of dissimilar mating types," said Donna.

"What about it? I have a video for it."

"No, thank you," said Donna. "No, I just like that phrase. I think it describes us."

"Well, obviously, Donna. That's what the video explains."

"Not what I meant," said Donna, laying back down.

"I know," said the Doctor, curling back next to her.

"Spaceman."

"Earth girl."


End file.
